--- a/src/hotspot/share/gc/shenandoah/shenandoahRootVerifier.cpp	Thu Oct 17 20:27:44 2019 +0100
+++ b/src/hotspot/share/gc/shenandoah/shenandoahRootVerifier.cpp	Thu Oct 17 20:53:35 2019 +0100
@@ -28,10 +28,12 @@
 #include "classfile/classLoaderDataGraph.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "code/codeCache.hpp"
+#include "gc/shenandoah/shenandoahAsserts.hpp"
 #include "gc/shenandoah/shenandoahHeap.hpp"
 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
 #include "gc/shenandoah/shenandoahRootVerifier.hpp"
 #include "gc/shenandoah/shenandoahStringDedup.hpp"
+#include "gc/shenandoah/shenandoahUtils.hpp"
 #include "gc/shared/weakProcessor.inline.hpp"
 #include "memory/universe.hpp"
 #include "runtime/thread.hpp"
@@ -52,36 +54,50 @@
   return (_types & type) != 0;
 }
 
+ShenandoahRootVerifier::RootTypes ShenandoahRootVerifier::combine(RootTypes t1, RootTypes t2) {
+  return static_cast<ShenandoahRootVerifier::RootTypes>(static_cast<uint>(t1) | static_cast<uint>(t2));
+}
+
 void ShenandoahRootVerifier::oops_do(OopClosure* oops) {
   CodeBlobToOopClosure blobs(oops, !CodeBlobToOopClosure::FixRelocations);
   if (verify(CodeRoots)) {
+    shenandoah_assert_locked_or_safepoint(CodeCache_lock);
     CodeCache::blobs_do(&blobs);
   }
 
   if (verify(CLDGRoots)) {
+    shenandoah_assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
     CLDToOopClosure clds(oops, ClassLoaderData::_claim_none);
     ClassLoaderDataGraph::cld_do(&clds);
   }
 
   if (verify(SerialRoots)) {
+    shenandoah_assert_safepoint();
     Universe::oops_do(oops);
     Management::oops_do(oops);
     JvmtiExport::oops_do(oops);
-    JNIHandles::oops_do(oops);
     ObjectSynchronizer::oops_do(oops);
     SystemDictionary::oops_do(oops);
   }
 
+  if (verify(JNIHandleRoots)) {
+    shenandoah_assert_safepoint();
+    JNIHandles::oops_do(oops);
+  }
+
   if (verify(WeakRoots)) {
+    shenandoah_assert_safepoint();
     AlwaysTrueClosure always_true;
     WeakProcessor::weak_oops_do(&always_true, oops);
   }
 
   if (ShenandoahStringDedup::is_enabled() && verify(StringDedupRoots)) {
+    shenandoah_assert_safepoint();
     ShenandoahStringDedup::oops_do_slow(oops);
   }
 
   if (verify(ThreadRoots)) {
+    shenandoah_assert_safepoint();
     // Do thread roots the last. This allows verification code to find
     // any broken objects from those special roots first, not the accidental
     // dangling reference from the thread root.
@@ -90,6 +106,8 @@
 }
 
 void ShenandoahRootVerifier::roots_do(OopClosure* oops) {
+  shenandoah_assert_safepoint();
+
   CodeBlobToOopClosure blobs(oops, !CodeBlobToOopClosure::FixRelocations);
   CodeCache::blobs_do(&blobs);
 
@@ -117,6 +135,8 @@
 }
 
 void ShenandoahRootVerifier::strong_roots_do(OopClosure* oops) {
+  shenandoah_assert_safepoint();
+
   CodeBlobToOopClosure blobs(oops, !CodeBlobToOopClosure::FixRelocations);
 
   CLDToOopClosure clds(oops, ClassLoaderData::_claim_none);